Year	Cases per 100,000
1990	3.7
1991	5.9
1992	6.4
1993	9.9
1994	12.9
1995	17.4
1996	19.5
1997	19.1
1998	19.7
1999	19.4
2000	20.7
2001	23.4
2002	26.6
2003	29.4
2004	30.1
2005	31.4
2006	31.4
2007	31.6